Stainless ferrous alloy



provement. of stainless irons and steels by inplained, renders the-steel fibrous and impairs its 5 s5 man an s r zirconium, a a gr ater a inity is" further obvious that with a manganese con- 35 no In my improved ferrous alloy, stainless iron centage of sulphur present,

than A... 5, 93; 1 A I 2,052,136

yumrao STATES PATENT oF-iuci:

I James P. Gill, 2a., alsl nor to Vanadiom-Alloys Steel Company, Latrobe, Pau a corporation of Pennsylvania No Drawing. Application January '1, 1933,

. Serial No. 050,738

1 Claim. (ci. rs-rzs) This application is in part a continuation of in almost all steels, but I have discovered that my patent application Serial Number 495,423, a manganese content in excess 01' 0.25% will re-. filed Novembei 1930. suit in the formation of an appreciable amount The purpose which I have in view is the imof manganese sulphides which, as above excreasing their machinability. physical and stainless qualities.

Certain stainless steels are formed with a chro- By the use of my improved process I produce mium content of from 8% to 20% and a carbon sulphides of chromium in the steel so that an content of less than 1%, and with or without a ultimate analysis will show the product to con- 10 content of less than 2% of nickel, tungsten tain up to 0.50%sulphur, the desirable range to 10 and/or molybdenum, and with or without a conobtain the improved properties being between tent of less than 0.50% of silicon,m'anganese 0.15% and 050%. and/or phosphorus. However, these types of A heat of my improved steel, having an ultistainless steels are notoriously hard to machine mate .analysis of carbon 0.12%; chromium and therefore'their use for many industrial pur- 12.75%; manganese 0.15%; silicon 0.30%; 15 poses, for which they are otherwise adapted, is phosphorus 0.13% and sulphur 0.23%, when anrestricted. nealedto a hardness approximating 190 Brinell It is known that the addition of sulphur to can be machined approximately three times. as steel increases machinability. Thus attempts rapidly as can steel of the same composition but go. have been made to improve such steels by the lacking a similar percentage of the sulphur in addition of a p r n ent under 0.15% tothey form of sulphides of chromium as an ingregether with a manganese content of approxidient. Steel of this same heat, when quenched mately 1% and a phosphorus content of apirom a temperature of 1'750 Fahr. and drawn to proximately 0.10%, but this results in the for- 1035 Fahr. disclosed the following physical manganese u p de w c renders qualities:-tenslle strength 125000 pounds; yield 25 the steel fibrous and thus impairs its physical point 112000 pounds; reduction in area 62%; qualities requisite for many uses. I elongationin two inches 18.5%, and Brinell'hard Again, it has been proposed to add the sillness 248. phur in the form of zirconium sulphide or to It is obvious to' those familiar with this branch add to the mix sulphur and zirconium, but the ct metallurgy that in my improved stainless 80 presence of zirconium renders the steel brittle, ferrous alloy the sulphur is present as a sulphide thus reducing its bil y a mp r ng its of chromium. If it were present as a sulphide of physical properties. iron the steel would not possess the high forge- In both the above instances the added metal, ability which it has been shown to possess. It

for the sulphur than has the chromium, and thus tent of 0.25% or less the sulphur is not present the ferrous alloy contains manganese sulphides in the form of manganese sulphide as the amount or zirconium sulphides, and the chromium r of manganese would be insumcient toabsorb an mains as chromium metal.. appreciable amount of the considerable pero st the sulphur is m in d with the (2110- Where zirconium is used as an ingredient the mium to form sulphides of chromium, either very purpose is to take up the sulphur and form chromic or chromous sulphides or both,- and I zirconium sulphide accomplish this result by adding the sulphur in The fom in Whichthe sulphur is present in '45 the m the form of sulphide of stainless ferrous alloys is very important. If it mus sulphide or iron pyrite The mm has less be in the form of manganese sulphide, the coramnity for the sulphur than has chromium, and rosionqesistmg uanties of the am M 1m thus when the mix is melted the sulphur leaves y e the iron and combines with the chromium, the paired and its structure is rendered fibrous If iron remaining as a necessary ingredient of the it be in thetform of zirmniumsmpmde the alloy 50 ferrous alloy and not as a deleterious intruder is more bfl such as manganese or zirconium or not as in- Bah-Of these Ingredients, manganese and 1?:-

troducing a new alloy in the mix as would be the conium are known to have a e r a finity 1501' case if copper matte were used as an ingredient. sulphur than has chromium, so it makes no dii' A certain percentage of manganese is present ference in the ultimate result whether the sul 55 phur and the manganese or the zirconium are added separately or in the form of sulphides.

Again the machining qualities oi my improved ferrous alloy are ifar superior at any hardness than those at the same hardness of a corresponding steel not having as a constituent sulphides of chromium within the limits above set forth.

The use of sulphide of ehrorniumas a constituent of my steel does not appreciably decrease the resistance of the steel to staining or corrosion, and samples tested under the standard salt spray test show my steel to have substantially the some corrosion resistance as do similar steels which lack the sulphide of chromium content.

The physical qualities of my improved stainless steel may be further improved by the addition of not more than 2% of nickel.

I claim:--

A stainless ferrous alloy having improved machinability without substantially impaired forgeability and consisting essentially of carbon from .05% to 50%; chromium from 8% to 20%; silicon from .10% to 50%; manganese from .05%

' to 25%; phosphorusirom a trace to .04%; sul- JAMS P. GILL. l5 

